contract cancelled but they still charging me

I cancelled my cell c Contract early and was told to pay R745.00 to cancell it two months early. I received an email from the retentions department stating that the contract is cancelled and my last bill would be the end of october. Now end of november they debited my account for another R370.80. When i called them i was told it would be escalated to the back office and not that its a suprise but i have not had any feedback from them. i tried calling them again today only to be transfered to another department and ive been holding on for 29minutes already. So again its costing me money to try and get my money back from them that they took of in error Please assist asap

Regards Kim